While the
finding of oiled birds may be an initial indication of the occurrence of
some spills (D133.1.w1)
(and may be the only indication of a small spill), assessment and
monitoring of an oil spill incident should usually be the first activity
in oiled wildlife response. (D183.w6)

"A
competent incident assessment will be key to a successful response, and
will help determine the magnitude and nature of the response needed."
(D183.w6)

Priority oiled wildlife response actions in the event of an oil spill
will be decided on the basis of the assessment of the incident, both
initially and on a daily basis as the incident develops and progresses. (D183.w6)

In the event of a spill it is important to determine:

Whether wild animals (birds, mammals, reptiles, amphibians) are at
risk from the spill;

The number of individuals oiled or at risk of oiling;

Any risk to endangered, rare or culturally important species or
populations;

Appropriate wildlife-orientated response activities;

Priorities for response;

Whether or not different response options are appropriate (e.g.
whether uncontaminated habitat is available nearby if birds are to be
hazed from oiled areas);

General oil
spill response uses the "tiered response" concept, in which
spills are classified as Tier One (small spills requiring only local
resources for clean up), Tier Two (medium sized spills requiring a
regional response) and Tier Three (large spills in which a national
response is required). (W468.Jan2003.w1)

The requirements for oiled wildlife response can also be considered
using the tiered response concept.

When individual wild animals are oiled,
or when a spill contaminates only a few individuals, local wildlife
rehabilitators/wildlife hospitals may be able to respond without any
assistance. (D214)

When more animals are involved, beyond the capabilities of
local organisations, a regional response may be required.

For spills
involving hundreds or thousands of wildlife casualties, a national or even
international response effort may be needed.

It has been suggested that, while the initial response assessment
should indicate the required scale of response, if there is doubt
regarding the level of response then a "worst case" scenario
should be prepared for, since it is easier to reduce the scale of the
operation than to increase it. (D183.w7)

Presence at different seasons, including changes during the spring and autumn migratory
periods;

Data on abundance (i.e. actual numbers counted per calendar week) and when the last survey was
conducted;

Data on which species and species groups (e.g. gulls, waders) are present, so that areas where the species most vulnerable to oil spills are found, and where colony breeding birds nest, have been
identified;

Data on endangered and rare species, to allow rapid protection of these species.

Further information on data which should be included in contingency
plans is included in the description of the Data Section within Oil Spill Contingency Planning
- Sections of the Wildlife Response Contingency Plan

The threat to
wild animal populations will vary depending on exactly where the oil is
spilled and its rate and direction of movement. For appropriate assessment
it is therefore necessary that those responsible for wildlife response
assessment have access to accurate, timely information regarding the
position and actual and projected movement of any oil slick.

This requires good communication and liaison with those responsible for
the general oil spill response, who should have this
information. Integration of the oiled wildlife response plan with the
general oil spill response promotes accessibility of such information.
(D183.w6)

Information about oil movement is also required in order to avoid
potentially counter-productive response activities, such as dispersing
birds into areas which might become contaminated. (D160.3.w3)

When a spill is notified, the available data bank should be consulted. If there
are notable populations of water birds or vulnerable mammals in the area, or if there is insufficient data available,
then preliminary surveys of the area are required.
(D10)

Both aerial and ground reconnaissance surveys should be conducted to
determine wildlife resources at risk. The main objectives of the surveys
are to evaluate the number, species and locations of wildlife which may be
affected by the spill, and the extent of oiling of individuals which has
already occurred. (D60.6.w6,
D160.3.w3)

Initial surveys should be conducted as soon as possible, preferably within three hours for aerial
surveillance and within six hours for ground surveillance.
(D10)

Aerial surveillance

For aerial surveillance, flights at under 100m will allow accurate identification of bird species. Aircraft involved in
wildlife surveillance should fly at about 100 km/hr. Surveillance by helicopter is ideal, but it can also be carried out from fixed-wing aircraft. An experienced ornithologist is required
[and should be identified prior to the spill] to carry out the survey
effectively, in order to identify species and record relevant characteristics, including
behaviour. This survey will not allow assessment of the number of oiled birds, but may indicate locations of birds in difficulties.
(D10, D160.3.w3)

The number of birds present in the area (hundreds, thousands or tens of thousands). this information may make a huge difference in
personnel and equipment required.

Species present, particularly endangered species and those which are very vulnerable to
oiling. Presence of large numbers of vulnerable species suggests that preparations should be made for opening of cleaning and rehabilitation
centres.

The location of birds in relation to the distribution and movements of the oil. If oil will drift towards large concentrations of birds within hours, then rapid initiation of
deterrence is required.

For maximum effectiveness of response options, they must be
instigated in a timely manner. (D10,
D160.3.w3,
B188,
D9, D160.4.w4,
J313.40.w3, P62.1.w1)

In the event of a spill, decisions on response options will have to be made based not
only on pre-recognised priority areas but also on practicalities:
whether or not it is possible to protect an area, and allowing for if
priority areas have already been impacted. (D60.2.w2)

Decisions on response options may have to balance the needs of
different types of organisms: sometimes what is best in order to reduce oiling of birds may
conflict with what is best for other fauna and flora affected by the
oil. (D193)

Losses due to scavenging of small birds will tend to be greater
than losses due to scavenging of large birds, since the whole body
may be carried off, rather than pieces eaten with parts remaining
to be found by search and collection personnel. (D159.II.w2)

In general there are more scavengers on coastal beaches than in estuaries, so more carcasses will be scavenged from coastal
beaches. (D159.II.w2)

Search efficiency: this will be affected by the search method (e.g.
on foot or by vehicle), by the size and colour of the casualties
(small individuals may be less easy to spot than larger ones) and
because individuals may seek shelter in dunes or vegetation some
distance from water and away from the main search area. (D183.w6)

Oiled individuals may leave the area after oiling and never be
found; (D183.w6)

Members of the public may remove or bury carcasses. (D159.II.w2,
D183.w6)

Assessment of birds lost at sea;
factors affecting recovery rates

In near-shore incidents most birds are likely to still be alive when
arriving on shore and losses at sea may be considered insignificant.
however for offshore spills such losses may be considerable. (D183.w6)

It may be necessary to make an estimate of the number of oiled
casualties lost at sea. (D183.w6)

This may involve drift experiments to assess the likelihood of
oiled birds being washed ashore. (D183.w6)

The species involved in a spill may affect recovery rates. Pelagic
species tend to avoid coming out onto beaches even when oiled,
therefore are more likely to die at sea than are bay or estuary
species which are more likely to haul out when oiled. (D159.II.w2)

Wind direction affects the rate of recovery: onshore winds will tend
to push animals ashore, while offshore winds may keep them away from
shore for longer. (D159.II.w2)

The longer that a carcass is kept away from shore, the more
likely it is that it will sink before becoming beached. (D159.II.w2)

The greater the distance that a carcass must drift to reach the
shore, the greater the chance that it will sink before becoming
beached: in general, even in calm water carcasses will begin sinking
after 10 to 14 days and sinking will occur sooner in rough water. (D159.II.w2)